#define _CRT_SECURE_NO_WARNINGS
#include<vector>
using namespace std;
class Solution
{
    int m, n;
    bool check[301][301];
    int dx[4] = { -1,1,0,0 };
    int dy[4] = { 0,0,-1,1 };
public:
    int numIslands(vector<vector<char>>& grid)
    {
        m = grid.size();
        n = grid[0].size();
        int ret = 0;
        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
            {
                if (grid[i][j] == '1' && check[i][j] == false)
                {
                    ret++;
                    check[i][j] = true;
                    dfs(grid, i, j);
                }
            }
        }
        return ret;
    }
    void dfs(vector<vector<char>>& grid, int i, int j)
    {
        for (int k = 0; k < 4; k++)
        {
            int x = dx[k] + i;
            int y = dy[k] + j;
            if (x >= 0 && x < m && y >= 0 && y < n && check[x][y] == false && grid[x][y] == '1')
            {
                check[x][y] = true;
                dfs(grid, x, y);
            }
        }
    }
};
int main()
{
    vector<vector<char>> grid({ {'1','1','1','1','0'},{'1','1','0','1','0'},{'1','1','0','0','0'},{'0','0','0','0','0'} });
    Solution().numIslands(grid);
    return 0;
}